Proof-of-principle of a lung sealant based on functionalized polyoxazolines: experiments in an ovine acute aerostasis model

OBJECTIVES

More effective lung sealants are needed to prevent prolonged pulmonary air leakage (AL). Polyoxazoline-impregnated gelatin patch (N-hydroxysuccinimide ester functionalized poly(2-oxazoline)s; NHS-POx) was promising for lung sealing ex vivo. The aim of this study is to confirm sealing effectiveness in an in vivo model of lung injury.

METHODS

An acute aerostasis model was used in healthy adult female sheep, involving bilateral thoracotomy, amputation lesions (bronchioles Ø > 1.5 mm), sealant application, digital chest tube for monitoring AL, spontaneous ventilation, obduction and bursting pressure measurement. Two experiments were performed: (i) 3 sheep with 2 lesions per lung (N = 4 NHS-POx double-layer, N = 4 NHS-POx single-layer, N = 4 untreated) and (ii) 3 with 1 lesion per lung (N = 3 NHS-POx single-layer, N = 3 untreated). In pooled linear regression, AL was analysed per lung (N = 7 NHS-POx, N = 5 untreated) and bursting pressure per lesion (N = 11 NHS-POx, N = 7 untreated).

RESULTS

Baseline AL was similar between groups (mean 1.38-1.47 l/min, P = 0.90). NHS-POx achieved sealing in 1 attempt in 8/11 (72.7%) and in 10/11 (90.9%) in >1 attempt. Application failures were only observed on triangular lesions requiring 3 folds around the lung. No influences of methodological variation between experiments was detected in linear regression (P > 0.9). AL over initial 3 h of drainage was significantly reduced for NHS-POx [median: 7 ml/min, length of interquartile range: 333 ml/min] versus untreated lesions (367 ml/min, length of interquartile range: 680 ml/min, P = 0.036). Bursting pressure was higher for NHS-POx (mean: 33, SD: 16 cmH2O) versus untreated lesions (mean: 19, SD: 15 cmH2O, P = 0.081).

CONCLUSIONS

NHS-POx was effective for reducing early AL, and a trend was seen for improvement of bursting strength of the covered defect. Results were affected by application characteristics and lesion geometry.

Suitable Patient Selection and Optimal Timing of Treatment for Persistent Air Leak after Lung Resection

OBJECTIVES

The choice of therapeutic intervention for postoperative air leak varies between institutions. We aimed to identify the optimal timing and patient criteria for therapeutic intervention in cases of postoperative air leaks after lung resection.

METHODS

This study utilized data from a prospective multicenter observational study conducted in 2019. Among the 2187 cases in the database, 420 cases with air leaks on postoperative day 1 were identified. The intervention group underwent therapeutic interventions, such as pleurodesis or surgery, while the observation group was monitored without intervention. A comparison between the intervention group and the observation group were analyzed using the cumulative distribution and hazard functions.

RESULTS

Forty-six patients (11.0%) were included in the intervention group. The multivariate analysis revealed that low body mass index (p = 0.019), partial resection (p = 0.010), intraoperative use of fibrin glue (p = 0.008), severe air leak on postoperative day 1 (p < 0.001), and high forced expiratory volume in 1 s (p = 0.021) were significant predictors of the requirement for intervention. The proportion of patients with persistent air leak in the observation group was 20% on postoperative day 5 and 94% on postoperative day 7. The hazard of air leak cessation peaked from postoperative day 3 to postoperative day 7.

CONCLUSIONS

This research contributes valuable insights into predicting therapeutic interventions for postoperative air leaks and identifies scenarios where spontaneous cessation is probable. A validation through prospective studies is warranted to affirm these findings.

Evaluating and developing sealants for the prevention of pulmonary air leakage: A systematic review of animal models

Sealants may provide a solution for pulmonary air leakage (PAL), but their clinical application is debatable. For sealant comparison, standardized animal models are lacking. This systematic review aims to assess methodology and quality of animal models for PAL and sealant evaluation. All animal models investigating lung sealing devices (e.g., staplers, glues, energy devices) to prevent or treat PAL were retrieved systematically from Embase, Pubmed and Web of science. Methodological study characteristics, risk of bias, reporting quality and publication bias were assessed. A total of 71 studies were included (N  =  75 experiments, N  =  1659 animals). Six different species and 18 strains were described; 92% of experiments used healthy animals, disease models were used in only six studies. Lesions to produce PAL were heterogenous, and only 11 studies used a previously reported technique, encompassing N  =  5 unique lesions. Clinically relevant outcomes were used in the minority of studies (imaging 16%, air leak 10.7%, air leak duration 4%). Reporting quality was poor, but revealed an upward trend per decade. Overall, high risk of bias was present, and only 18.7% used a negative control group. All but one study without control groups claimed positive outcomes (95.8%), in contrast to 84.3% using positive or negative control groups, which also concluded equivocal, adverse or inconclusive outcomes. In conclusion, animal studies evaluating sealants for prevention of PAL are heterogenous and of poor reporting quality. Using negative control groups, disease models and quantifiable outcomes seem important to increase validity and relevance. Further research is needed to reach consensus for model development and standardization.

Index hospital cost of adverse events following thoracic surgery: a systematic review of economic literature

OBJECTIVES

Adverse events (AEs) following thoracic surgery place considerable strain on healthcare systems. A rigorous evaluation of the economic impact of thoracic surgical AEs remains lacking and is required to understand the value of money of formal quality improvement initiatives. Our objective was to conduct a systematic review of all available literature focused on specific cost of postoperative AEs following thoracic surgery.

DESIGN

Systematic review of the economic literature was performed, following recommendations from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement.

DATA SOURCES

An economic search filter developed by the Canadian Agency for Drugs and Technologies in Health was applied, and MEDLINE, Embase and The Cochrane Library were searched from inception to January 2022.

ELIGIBILITY CRITERIA

We included English articles involving adult patients who underwent a thoracic surgical procedure with estimated costs of postoperative complications. Eligible study designs included comparative observational studies, randomised control trials, decision analytic or cost-prediction models, cost analyses, cost or burden of illness studies, economic evaluation studies and systematic reviews and/or meta-analyses of cost analyses and cost of illness studies.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently screened titles and abstracts in the first stage and full-text articles of included studies in the second stage. Disagreements during abstract and full-text screening stages were resolved via discussion until a consensus was reached. Studies were appraised for methodological quality using the Critical Appraisal Skills Program checklist.

RESULTS

3349 studies were identified: 20 met inclusion criteria. Most were conducted in the USA (12/20), evaluating AE impact on hospital expenditures (18/20). 68 procedure-specific AE mean costs were characterised (USD$). The most commonly described were anastomotic leak (mean:range) (USD$49 278:$6 176-$133 002) and pneumonia ($12 258:$2608-$34 591) following esophagectomy, and prolonged air leak ($2556:$571-$3573), respiratory failure ($19 062:$11 841-$37 812), empyema ($30 189:$23 784-$36 595), pneumonia ($15 362:$2542-$28 183), recurrent laryngeal nerve injury ($16 420:$4224-$28 616) and arrhythmia ($6835:$5833-$8659) following lobectomy.

CONCLUSIONS

Hospital costs associated with AEs following thoracic surgery are substantial and varied. Quantifying costs of AEs enable future economic evaluation studies, which could help prioritising value-directed quality improvement to optimally improve outcomes and reduce costs.

The Role of Sublobar Resection for the Surgical Treatment of Non-Small Cell Lung Cancer

Lung cancer is the most common cancer killer in the world. The standard of care for surgical treatment of non-small cell lung cancer has been lobectomy. Recent studies have identified that sublobar resection has non-inferior survival rates compared to lobectomy, however. Sublobar resection may increase the number of patients who can tolerate surgery and reduce postoperative pulmonary decline. Sublobar resection appears to have equivalent results to surgery in patients with small, peripheral tumors and no lymph node disease. As the utilization of segmentectomy increases, there may be some centers that perform this operation more than other centers. Care must be taken to ensure that all patients have access to this modality. Future investigations should focus on examining the outcomes from segmentectomy as it is applied more widely. When employed on a broad scale, morbidity and survival rates should be monitored. As segmentectomy is performed more frequently, patients may experience improved postoperative quality of life while maintaining the same oncologic benefit.

Neoveil versus TachoSil in the treatment of pulmonary air leak following open lung surgery: a prospective randomized trial

OBJECTIVES

Prolonged air leak (PAL) is often associated with pain and immobilization and is a major limiting factor for discharge from the hospital. The efficacy of 2 surgical patches was investigated in the treatment of air leak following open surgery.

METHODS

Forty-five patients were randomized in a 1:1 ratio either to treatment with Neoveil (polyglycolic acid) (n = 22) or TachoSil (collagen sponge) (n = 23). Air leak was monitored at 2, 4, 8, 12 and 24 h after surgery and then daily at 8 am and 6 pm, using a digital recording system. The primary outcome was the time to air leak closure. Secondary outcomes were incidence, air leak intensity, incidence of PAL and incidence of pneumonia.

RESULTS

Air leak 2 h after surgery was observed in 11/22 (50%) vs 14/23 (61%) patients treated with polyglycolic acid, respectively, with collagen sponge. On average, air loss within the first 24 h after surgery was lower and declined faster in patients treated with polyglycolic acid. Time to pulmonary air leak closure was somewhat shorter with polyglycolic acid (median [interquartile range] 10 [2, 52] h) compared to collagen sponge (19 [2, 141] h). However, the difference was not statistically significant (P = 0.35, Wilcoxon rank-sum test). PAL occurred in 3/22 (14%) vs 6/23 (26%) patients, and pneumonia occurred in 2/22 (9%) vs 3/23 (13%) patients treated with polyglycolic acid, respectively, collagen sponge.

CONCLUSIONS

Both systems are effective in the treatment of air leak. Our results suggest a possible superiority of Neoveil over TachoSil in post-surgery air leak control.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04065880.

Clinical and Economic Burden Associated with Prolonged Air Leaks Among Patients Undergoing Thoracic Resection: A Retrospective Database Analysis

Purpose

Prophylactic use of lung sealants among patients undergoing thoracic resection has been reported for the management of intraoperative air leaks and is associated with a lower incidence of prolonged air leak (PAL) and a shorter length of stay (LOS). This study estimated the incremental economic and clinical burden of PAL among patients with lung sealants used during thoracic resection in the United States.

Patients and Methods

This retrospective analysis examined hospital data (Premier Healthcare Database) for adults (age ≥18 years) with inpatient thoracic resection between October 2015 - March 2021 (first admission=index) and lung sealant used during their procedure. Follow-up extended through 90 days post-discharge. Patients were grouped by presence/absence of PAL (ie, diagnosis of post-procedural air leak or post-procedural pneumothorax with associated LOS exceeding 5 days). Outcomes included intensive care unit (ICU) days, total index hospital costs, all-cause 30-, 60-, and 90-day readmission, discharge status, and in-hospital mortality. Generalized linear models quantified associations between PAL and outcomes, accounting for hospital-level clustering, and patient, procedure, and hospital/provider characteristics.

Results

Among the 9727 patients included for study (51.0% female, 83.9% white, mean age 66 years), 12.5% had PAL, which was associated with significant incremental increases in ICU days (0.93 days, p<0.001) and total hospital cost ($11,119, p<0.001). PAL also decreased the likelihood of discharge to home (from 91.3% to 88.1%, p<0.001) and increased the risk of readmission within 30, 60, and 90 days by up to 34.0% (from 9.3% to 12.6%;11.7% to 15.4%;13.6% to 17.2%, respectively), all p<0.01. Absolute risk of mortality was low, but two times higher in patients with PAL versus those without PAL (2.4% vs 1.1%, p=0.001).

Conclusion

This analysis demonstrates that despite the prophylactic use of lung sealants, PAL continues to put a burden on the healthcare system, highlighting an unmet need for improved sealant technology.

Exploring consensus for the optimal sealant use to prevent air leak following lung surgery: a modified Delphi survey from The European Society of Thoracic Surgeons

OBJECTIVES

The use of sealants is one of the methods available to reduce the occurrence of intraoperative air leaks. The objective of this modified Delphi survey among ESTS members is to understand the attitudes of clinicians to the optimal use of sealants in air leak management.

METHODS

To understand the attitudes of a wider sample of clinicians, a questionnaire was developed highlighting key issues through 37 statements. Respondents were invited to score their level of agreement with each. A modified Delphi methodology was used to review responses with a threshold of agreement for consensus of 75%.

RESULTS

A total of 258 responses were received (response rate 17%). Respondents agreed that prolonged air leaks are a common complication in thoracic surgery presenting a burden to the patient and increasing the costs of care. There is clear support for the use of sealants to reduce costs and improve the efficiency of healthcare provision and duration of chest tube use in selected high-risk patients with intraoperative air leak at the end of the lung surgery. Respondents also agreed that, due to often complex nature of thoracic surgery, sealants should be developed specifically for this application.

CONCLUSION

There is a clear role for sealants in the management of air leaks and certain surgical procedures demand their use (i.e. lung volume reduction surgery, decortication). This opinion-based consensus review helps to raise the debate about the burden of air leaks in thoracic surgery in order that this issue is recognized in practice and informs the optimal use of sealants in lung surgery.

Efficacy of Alaska pollock gelatin sealant for pulmonary air leakage in porcine models

BACKGROUND

Postoperative prolonged air leakage is a frequent complication following lung resection. We have developed a new sealant based on a hydrophobically modified Alaska pollock-derived gelatin (ApGltn) sealant. The purpose of this study was to evaluate the adhesive strength of the ApGltn sealant in comparison with a fibrin sealant using a new spray system in ex vivo and in vivo models.

METHODS

Pleural defects in ex vivo and in vivo porcine models were created, to which the ApGltn sealant or the fibrin sealant was applied. The pressure resistance was assessed with a stepwise increase in airway pressure to confirm air leakage from the sealing site. Tissue samples covered with each sealant were obtained for histologic assessment.

RESULTS

In the ex vivo experiment, the leak pressures of the ApGltn sealant were significantly greater than those of the fibrin sealant (102.94 ± 15.6 cmH₂O and 28.37 ± 5.1 cmH₂O, respectively) (p < 0.01). In the in vivo experiment, the leak pressures of the ApGltn sealant were also significantly greater than those of the fibrin sealant (68.82 ± 18.04 cmH₂O and 43.33 ± 7.13 cmH₂O, respectively) (p = 0.043). The histologic examination confirmed that the ApGltn sealant adhered tightly to both the pleura and the surface of the pleural defect.

CONCLUSIONS

The ApGltn sealant has sufficiently high adhesive quality in ex vivo and in vivo porcine lungs, which could be considered suitable and effective for use in the prevention of air leakage from the lungs.